Development of a Process Signature for Manufacturing Processes with Thermal Loads

Frerichs, F.; Meyer, Heiner; Strunk, Rebecca; Kolkwitz, B.; Épp, Jérémy

doi:10.1007/s11661-018-4719-8

Cited by 7 publications

(4 citation statements)

References 17 publications

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“…This means that the depth of the 1st zero-crossing The reason for the systematic deviation to lower values is not fully understood. Maybe relaxation processes reduce the stresses [30]. The observation that the measured residual stresses are lower than the calculated data is also overserved by other authors [17,25] for laser and induction hardening.…”

Section: The 1st Zero-crossing Of the Residual Stress Distributionmentioning

confidence: 49%

Process Signature for Laser Hardening

Frerichs

Lübben

et al. 2021

Metals

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During many manufacturing processes for surface treatment of steel components heat will be exchanged between the environment and the workpiece. The heat exchange commonly leads to temperature gradients within the surface near area of the workpiece, which involve mechanical strains inside the material. If the corresponding stresses exceed locally the yield strength of the material residual stresses can remain after the process. If the temperature increase is high enough additionally phase transformation to austenite occurs and may lead further on due to a fast cooling to the very hard phase martensite. This investigation focuses on the correlation between concrete thermal loads such as temperature and temperature gradients and resulting modifications such as changes of the residual stress, the microstructure, and the hardness respectively. Within this consideration the thermal loads are the causes of the modifications and will be called internal material loads. The correlations between the generated internal material loads and the material modifications will be called Process Signature. The idea is that Process Signatures provide the possibility to engineer the workpiece surface layer and its functional properties in a knowledge-based way. This contribution presents some Process Signature components for a thermally dominated process with phase transformation: laser hardening. The target quantities of the modifications are the change of the residual stress state at the surface and the position of the 1st zero-crossing of the residual stress curve. Based on Finite Element simulations the internal thermal loadings during laser hardening are considered. The investigations identify for the considered target quantities the maximal temperature, the maximal temperature gradient, and the heating time as important parameters of the thermal loads.

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Section: The 1st Zero-crossing Of the Residual Stress Distributionmentioning

confidence: 49%

Process Signature for Laser Hardening

Frerichs

Lübben

et al. 2021

Metals

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“…Figures 9,14,19,23 and 32 confirm this interpretation. The thermal effect dominates the results and leads to tensile stresses in the surface [12]. The slightly higher laser power of 800 W achieved a surface temperature of 1250 • C and leads to a full austenitization within the surface near area (approximately 200 µm).…”

Section: Laser Hardening and Meltingmentioning

confidence: 99%

“…Further investigations within the CRC [8][9][10][11][12][13][14] focus on internal material loads and modifications of single processes. The influence of different initial microstructures on the resulting modification due to single thermal impacts was investigated in [15].…”

Section: Introductionmentioning

confidence: 99%

The Influence of Former Process Steps on Changes in Hardness, Lattice and Micro Structure of AISI 4140 Due to Manufacturing Processes

Borchers

Clausen

Ehle

et al. 2021

Metals

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The surface and subsurface conditions of components are critical for their functional properties. Every manufacturing process modifies the surface condition as a consequence of its mechanical, chemical, and thermal impact or combinations of the three. The depth of the affected zone varies for different machining operations and is related to the process parameters and characteristics. Furthermore, the initial material state has a decisive influence on the modifications that lead to the final surface conditions. With this knowledge, the collaborative research center CRC/Transregio 136 “Process Signatures” started a first joint investigation to analyze the influence of several machining operations on the surface modifications of uniformly premanufactured samples in a broad study. The present paper focusses on four defined process chains which were analyzed in detail regarding the resulting surface conditions as a function of the initial state. Two different workpiece geometries of the same initial material (AISI 4140, 42CrMo4 (1.7225) classified according to DIN EN ISO 683-2) were treated in two different heat treating lines. Samples annealed to a ferritic-perlitic microstructure were additionally deep rolled as starting condition. Quenched and tempered samples were induction hardened before further process application. These two states were then submitted to six different manufacturing processes, i.e., grinding (with mainly mechanical or thermal impact), precision turning (mainly mechanical), laser processing (mainly thermal), electrical discharge machining (EDM, mainly thermal) and electrochemical machining (ECM, (mainly chemical impact). The resulting surface conditions were investigated after each step of the manufacturing chain by specialized analysis techniques regarding residual stresses, microstructure, and hardness distribution. Based on the process knowledge and on the systematic characterizations, the characteristics and depths of the material modifications, as well as their underlying mechanisms and causes, were investigated. Mechanisms occurring within AISI 4140 steel (42CrMo4) due to thermal, mechanical or mixed impacts were identified as work hardening, stress relief, recrystallization, re-hardening and melting, grain growth, and rearrangement of dislocations.

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“…The concept is equivalent to the evaluation of "Process or Manufacturing Signatures" [11], which similarly describes geometrical product variations depending on a given process condition. This method was adopted in the quality assessment of several manufacturing technologies such as milling [12], micromilling [13], grinding [14], laser polishing [15], additive manufacturing [16], and recently in replication technologies [17,18]. In [17] and [18], the replication fidelity of micro and nano structures, as well as sub-µm surface roughness, was found by measuring the IM insert and the plastic product in mirrored areas, finding a direct comparison of the features, and quantitative estimation of replication fidelity as the dimensional ratio between plastic and mold geometry.…”

Section: Introductionmentioning

confidence: 99%

Product Fingerprints for the Evaluation of Tool/Polymer Replication Quality in Injection Molding at the Micro/Nano Scale

Loaldi

Regi

et al. 2021

Nanomanuf Metrol

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Development of a Process Signature for Manufacturing Processes with Thermal Loads

Cited by 7 publications

References 17 publications

Process Signature for Laser Hardening

Process Signature for Laser Hardening

The Influence of Former Process Steps on Changes in Hardness, Lattice and Micro Structure of AISI 4140 Due to Manufacturing Processes

Product Fingerprints for the Evaluation of Tool/Polymer Replication Quality in Injection Molding at the Micro/Nano Scale

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